It is well known that absorbers used in the microwave industry are usually ferrites, carbides, nitrides and the like having a high density, and are mixed with binders and solvents to prepare absorbing materials. However, after the materials are stored for a period of time, sedimentation of the absorbers occurs, which negatively affects the coating process of the absorbing materials, thus negatively affecting the actual absorbing effect of the absorbing materials and the temperature stability. In this case, the temperature is more likely to be very high, thus causing safety problems.
In addition, when microwave appliances made of such absorbing materials are used for cooking, the food may have an over-cooked surface and uncooked insides, causing unsatisfied cooking results and thus affecting the consumer experience.
The above problems negatively affect the application of the absorbing materials in the microwave industry, thus making the absorbing materials unable to meet the growing demands of baking and cooking.
The absorbing material technology of the existing microwave industry mainly relates to procedures of adding the high-density absorber into the silica gel binder, adding a proper amount of an adjuvant, mechanical stirring, vulcanizing and cross-linking the mixture, pressing into a silica absorbing sheet having a thickness of about 2 mm (i.e., preparing the final absorbing layer), and adhering the absorbing sheet to the surface of the substrate with an adhesive to form a microwave absorbing appliance. However, a microwave baking tray made by above method has following disadvantages.
1. The absorber is not uniformly dispersed and easy to settle, which will result in a big difference in microwave absorbing properties of products having the same specification type in the same batch, and even cause a local overheating and melting of the products.
2. A large amount of the resin material such as a silica gel is used, resulting in an excessively thick absorbing layer.
3. The product has no far-infrared performance, and thus the inside of the food is not well-cooked.
4. The production process is complex, time-consuming and costly.
5. The product has no hydrophobic property and oily will be easily adhered after the product is used for a period.
In view of the fact that a coating type of an absorbing material is rarely seen in the art of the microwave industry, it is impossible to find an absorbing material having anti-settling, far-infrared and stable absorbing properties. Due to the complex process, the thick sheet and the lack of hydrophobic and oleophobic properties of the traditional absorbing materials, demands for the future developments cannot be realized. The absorbing coating having a thin layer, a simple applying process and good performances is still needed in the art.